Osteogenesis imperfecta (OI) is a genetic condition found in 1 in 15,000 births with around 50,000 sufferers in the United States. Manifested first in childhood, the underlying problem is a defect in type 1 collagen, the protein that forms the matrix framework for bone structure. It manifests as bones that break easily, even without trauma, and hence has been called Brittle Bone Disease. It is not uncommon for OI children to experience up to 100 breaks a year.
The condition presents as a spectrum of disorders categorized into eight types. As well as bones and teeth that fracture easily, some patients experience loose ligaments and joint displacements, others may have curved bones. All patients suffer from fatigue and bone and muscle pain. Mobility is restricted and normal everyday life of sufferers is impaired.
There is no cure for OI and the main treatment is aimed at encouraging sufferers to maintain a healthy life style. In certain cases patients may have metal rods inserted into long bones to prevent curvature and maintain strength.
The only effective drug treatment available today is anti-resorptive bisphosphonates. Normal bone turns over with old bone being removed (resorption) by the action of osteoclasts and new bone being generated by the action of osteoblasts. In OI there is an imbalance between the action of osteoclasts and osteoblasts. Bisphosphonates reduce the activity of osteoclasts and thus reduce the amount of old bone being resorbed which can help to maintain bone mass and allow the balance to be tilted more in favour of the osteoblasts.
There is a great medical need for safe and effective therapies to treat OI especially in children. Currently there is no approved therapy that will stimulate the amount of or action of osteoblasts.
Mesentech’s first product, C3, contains as the active therapeutic agent, an EP4 agonist, that stimulates the maturation of osteoblasts within the bone thus raising the number of bone forming osteoblast cells resulting in increased new bone. Mesentech believes that C3 can offer a major new treatment for OI providing generation of new and strong bone and as such provide can an adjunct or alternative to bisphosphonates, which just retain old bone.
Good treatment outcomes in OI could translate to and support the use of C3 for treatment of osteoporosis, often termed brittle bone disease of the elderly.